Heres the question exactly as is:
Tangents to the curve f(x)=4x-x^2 intersect at (7/4,11/2). P and Q are points of tangency to the curve. Find the point of intersection of the normals drawn to the curve at points P and Q.
I can only find the point on the left of the curve but i cant find anything about the point ont he right. helppp mee (sorta urgent unit final tomorrow).
(p.s. the answers are (1/2,7/4) its not the anwser im after how to do it)
December 2nd 2007, 05:24 PM
You can find the derivative of y to find the slope, m, at the points.
Solve for x. That will be the x-coordinates of the points of intersection of the two tangent lines.
You can then find their equations and it's downhill.